1. Fields of the Invention
The present invention concerns a photoactive nanocomposite capable of being used in a solar cell to induce the photovoltaic effect, in a light emitter or in a photodetector.
2. Description of the Related Art
This type of photoactive component conventionally comprises a donor-acceptor couple of semiconductor elements. It is known that to see a charge transfer between donor and acceptor, the respective energy levels of the former and the latter must be compatible.
Photovoltaic devices based on amorphous or thin film microcrystalline silicon are familiar. These devices deliver a significant output of 6 to 10%. However, they are not very stable (ageing). Materials of the interpenetrating network type—conjugated polymer and fullerene or its derivatives—are also familiar. The usefulness of these systems is limited in particular by the flow of charge in organic materials. Indeed, in most organic conductors, charge mobility is poor (less than 10−4 cm2Vs−1) because of the presence of charge traps such as oxygen. Furthermore, they are not very stable in air. A way of addressing this limitation in charge flow is to combine, for example, a conjugated polymer electron donor with an inorganic semi-conductor as the electron acceptor. The present invention concerns a new type of interpenetrating network including an organic compound and silicon nanowires. The organic compound may be an electron donor or acceptor and the silicon nanowires an electron acceptor or donor. The development of solar cells using such a material has not been considered to date.
Currently, entirely organic solar cells, which use an active material in interpenetrating networks, made of a mixture of conjugated polymer such as polyphenylenevinylene (donor), a fullerene derivative (acceptor), show photovoltaic conversion output of more than 3%, with a life of one hundred hours in controlled light and atmospheric conditions.